One user reporting a crash with no supporting information isn't really enough data to base an update on. It could just be a random crash that has nothing to do with your game.

If the customer is in contact with you, then get as much information out of him as possible before using the data to update, a 2.0 build probably won't fix anything broken in 2.1 as if it is something in your code it's probably just as broken in 2.0.